It is well known to use gas flow regulators in conjunction with supply sources of gases such as tanks of oxygen containing high pressure oxygen or oxygen gas mixtures, to control both the pressure and the rate of flow of the oxygen or oxygen mixture being released from the tank. More recently, there have been developed separate oxygen control devices that conserve the oxygen supply by limiting its release only during useful times, as for example, only during the inhalation period of the breathing cycle of a patient using the oxygen. Such devices are sensitive to drops in pressure caused by inhalation to activate the oxygen flow only during inhalation.
It also is known to provide in such devices an alternate flow path for the gas mixture or oxygen to be inhaled by the user, as for example a continuous flow by-pass path to be selectively controlled by actuating a valve in the gas flow by-pass path.
Because of the inherent properties of pressurized gases and the need to control carefully their flow rates for human use, we have invented a new microvalve for use in gas flow systems that both is simple in manufacture and will be accurate and reliable in use.